Huge knot of garter snakes emerge from hibernation

If you think one snake is scary enough, a US university professor has captured a natural phenomenon which will definitely send shivers slithering down your spine.

The photo taken by Professor Tracy Langkilde, Head of Biology at Pennsylvania State University, captured the moment a swarm of garter snakes emerged to find their mates after several months hibernating in communal dens.

Professor Langkilde told 7 News Online the dens are "limestone cavern systems that allow them to get deep enough that they avoid being frozen during the long hard winter".

In this particular den in southern Manitoba in Canada there were close to 10,000 garter snakes, the professor said.

"In early spring, as the earth begins to thaw, the snakes slowly emerge from these overwinter caverns," Professor Langkilde said.

Professor Langkilde said there were close to 10,000 snakes at this den. Source: Professor Tracy Langkilde

The mass exodus from hibernation is said to take place between late April and the end of May.

Following this, the males tend to stay close waiting for females as mating season gets underway.

"When a female emerges, several males aggregate around her and form large courting balls," Professor Langkilde said

Some males also change their pheromones so other males think they're female and slither on top of them as well.

"This not only warms the newly emerged male (who has been underground and cold for 9 months), but also protects him from crows that loiter around the dens and pick out the liver of cold and largely immobile snakes, " the biologist said.

Professor Langkilde said this image shows several males aggregating around a female. Source: Professor Tracy Langkilde

The image was shared by a local snake catcher, Stewart Lalor from Elite Snake Catching Services, on social media in the past week because it is mating season in Australia and the snakes' behaviour in Canada is incredibly rare.

Mr Lalor said snakes don't fare well in the cold temperatures and actually don't hibernate here.

"In Australia they just slow down a bit,” he told 7 News Online.

"They're pretty much active all year round."

For about three months Australian snakes go into “brumation”, a hibernation-like state where they become lethargic and sometimes stop moving.